EP 0 551 001 A1 discloses such a semiconductor chip and such a method for producing it. The known semiconductor chip has a light-generating region which is formed on a substrate and on which a thick window layer is located. The thickness of the window layer is dimensioned such that a light beam totally reflected on the upper side of the window layer can reach and/or leave through a side face of the window layer.
A disadvantage of the known semiconductor chip is the great thickness of the window layer, since layers of great thickness can only be epitaxially produced with difficulty. Furthermore, the known window layer only has a high coupling-out efficiency if the critical angle is not too large. However, the semiconductor chips for optoelectronics typically comprise semiconductor material with a refractive index of n=3.5. The substrate in contact with the semiconductor material usually has a refractive index of n=1.5. In this case, the critical angle for total reflection is approximately 26°. This has the consequence that, in the case of semiconductor chips in dice form, typically only approximately 4% of the photons generated couple out from the semiconductor chip.
In DE 199 11 717 A1, it has therefore been proposed to provide a multiplicity of active zones distributed over the semiconductor chip, over each of which a hemispherical radiation coupling-out element is arranged. This semiconductor chip offers the advantage that the radiation coupling-out elements have the ideal form best suited for coupling out, that is the form of a Weierstrass sphere. Furthermore, not too great a thickness is required for the layer from which the hemispherical radiation coupling-out elements are produced.
However, a disadvantage of the known semiconductor chip is that the contacting of the active zones is relatively complex, since the contacting takes place laterally on the hemispherical radiation coupling elements.
Finally, U.S. Pat. No. 5,087,949 A discloses a semiconductor chip in which the substrate itself has the function of a window layer. The substrate has laterally beveled side faces, so that a light beam emanating from an active zone impinges on the side face as far as possible at an angle of incidence which is smaller than the critical angle for total reflection. However, this solution cannot be applied in every case, since suitable substrates are often not available.